The ODP enterprise viewpoint focuses on the roles and policies on the enterprise that the system is meant to support. QoS-ODP management is now an important research topic for many universities, institutes and industrial organizations. Several approaches are being used in the field of the formalization of QoS-ODP. The use of formal methods in the design process of ODP systems is explicitly required. In this paper, we explore the benefits provided by using the proof construction approach to define the protocol of negotiating QoS requirements when the enterprise objects perform roles constrained by policies. In this context, we investigate the support for the specification of Quality of Service (QoS) in Event-B when modelling open distributed System in the enterprise viewpoint.